A statistical algorithm for detecting cognitive plateaus in Alzheimer’s disease

Repeated neuropsychological measurements, such as mini-mental state examination (MMSE) scores, are frequently used in Alzheimer’s disease (AD) research to study change in cognitive function of AD patients. A question of interest among dementia researchers is whether some AD patients exhibit transient “plateaus” of cognitive function in the course of the disease. We consider a statistical approach to this question, based on irregularly spaced repeated MMSE scores. We propose an algorithm that formalizes the measurement of an apparent cognitive plateau, and a procedure to evaluate the evidence of plateaus in AD using this algorithm based on applying the algorithm to the observed data and to data sets simulated from a linear mixed model. We apply these methods to repeated MMSE data from the Michigan Alzheimer’s Disease Research Center, finding a high rate of apparent plateaus and also a high rate of false discovery. Simulation studies are also conducted to assess the performance of the algorithm. In general, the false discovery rate of the algorithm is high unless the rate of decline is high compared with the measurement error of the cognitive test. It is argued that the results are not a problem of the specific algorithm chosen, but reflect a lack of information concerning the presence of plateaus in the data.     

Domestic violence, poverty, and social services: does location matter?

Objective. This study investigates whether or not domestic violence agencies are located in areas of need. Recent research indicates that community economic disadvantage is a risk factor for intimate partner violence, but related questions regarding the geographic location of social service agencies have not been investigated.Methods. Using Connecticut as a case study, we analyze the relationship of agency location and police-reported domestic violence incidents and assaults using OLS regression and correcting for spatial autocorrelation.Results. The presence of an agency within a town has no relationship with the rates of domestic violence. However, regional patterns are evident.Conclusion. Findings indicate that programs are not geographically mismatched with need, but neither are programs located in towns with higher rates of incidents or assaults. Future research and planning efforts should consider the geographic location of agencies.     

Comparison of older adult performance during the functional-reach and limits-of-stability tests

Despite widespread use of the functional-reach (FR) and limits-of-stability (LOS) tests, comparisons of postural strategies and postural limits for these tests have not been previously reported. The purpose of this study was to compare postural strategies as determined by cross-correlation analyses of trunk and lower leg angular displacements and postural limits as assessed by maximum center-of-gravity (COG) excursions as older adults at low fall risk completed the FR and LOS tests. Fourteen older adults completed three FR and LOS trials while standing on a Balance Master force platform. Results indicated that despite relatively similar instructions to reach or lean as far as possible without losing balance or altering the base of support, their performance differed with regard to postural strategies employed and maximum COG excursions produced. These findings suggest that because of differences in task constraints, FR and LOS tests should not be used interchangeably.     

On characteristic function-based bootstrap tests

The online version of the original article can be found at     

The energy constraint in the 1980s and the scope for import substitution in Western Europe

Various policies are being proposed for reducing the energy dependence of Western Europe during the 1980s. This paper discusses their impacts through the use of a simple simulation model under different assumptions concerning energy prices conservation measures and overall economic growth. It also assesses broad energy prospects for three regions of Western Europe up to 1990. In particular, the paper analyzes the scope for substituting domestically produced energy for imported energy. Tentative policy recommendations are presented following presentation of the results. Preference is expressed for combined price-cum-rationing measures. Coordinated and generalized energy consumption policies, so as to improve the energy efficiency for both intermediate and final uses, are also discussed.     

Changes in the Relationship Between Child Support Payments and Educational Attainment of Offspring, 1979–1988

We examine changes over the 1980s in the effect of child support payments on the educational attainment of children age 16 to 19 in the United States, and why child support has a stronger impact than other sources of income. We use 1979 and 1988 Current Population Survey data, covering a period when improvements in enforcement should have increased the proportion of reluctant fathers paying support. We hypothesize and find that the positive effect of child support on education diminished somewhat over this period, both absolutely and in relation to other income.     

The Role of Knowledge Bases in Complex Product Systems: Some Empirical Evidence from the Aero Engine Industry

In this paper we argue that the virtual corporation as understood in current management literature does not hold as a universal model throughout various industrial sectors. Complex product systems industries show peculiar features in terms of product characteristics, innovation dynamics and strategic and management options that may render the virtual corporation model inapplicable.The paper begins with a contrast between the simplistic neoclassical approach to the interpretation of the concept of knowledge and the more in-depth evolutionary view. The former understands knowledge as information and its production process and outcomes as easily decomposable. Based on this, advocates of virtual corporation claim the viability of outsourcing strategies based on simple economic factors. The evolutionary approach, on the other hand, considers knowledge as a system of processes deeply rooted in their contexts of production. Tacitness and non-decomposability of the knowledge production processes are highly emphasised in this view. In the light of this contrast and relying on a study of the aero engine industry we reinterpret the notion of virtual corporation showing its limits.     

The private journey: An interpretative phenomenological analysis of exclusive breastfeeding

Background

Exclusive breast milk provides complete nutrition for a baby’s first six months of life. In Australia, breastfeeding initiation rates are high, however duration rates are low. Although numerous studies have explored the reasons behind low levels of breastfeeding, few have examined the experiences of women who maintain exclusive breastfeeding for the recommended six-month duration.

Household structure and childhood immunization in Niger and Nigeria

In this study, we use data from the Demographic and Health Surveys to examine the relationship between household structure and childhood immunization in Niger and Nigeria. We show that household structure is an important determinant of childhood immunization in Nigeria: Children from nuclear, elementary polygynous, and three-generational households are worse-off than those from laterally extended households. However, the lower odds of full immunization among children from three-generational and elementary polygynous households are attributable to low economic status and low maternal education levels, respectively. In Niger, household structure does not have a significant effect on children’s likelihood of being fully immunized.     

Climate Change Beliefs and Perceptions of Weather‐Related Changes in the United Kingdom

Public perception research in different countries has suggested that real and perceived periods of high temperature strengthen people's climate change beliefs. Such findings raise questions about the climate change beliefs of people in regions with moderate climates. Relatively little is known about whether public concerns about climate change may also be associated with perceived changes in other weather‐related events, such as precipitation or flooding. We examine the relationship between perceived changes in weather‐related events and climate change beliefs among U.K. residents at a time of below‐average winter temperatures and recent flooding. National survey data (n = 1,848) revealed that heat waves and hot summers were perceived to have become less common during respondents’ lifetimes, while flooding, periods of heavy rainfall, coastal erosions, and mild winters were perceived to have increased in frequency and cold winters were perceived to be unchanged. Although perceived changes in hot‐weather‐related events were positively associated with climate change beliefs, perceived changes in wet‐weather‐related events were found to be an even stronger predictor. Self‐reported experience of “flooding in own area” and “heat‐wave discomfort” also significantly contributed to climate change beliefs. These findings highlight the importance of salient weather‐related events and experiences in the formation of beliefs about climate change. We link our findings to research in judgment and decision making, and propose that those wishing to engage with the public on the issue of climate change should not limit their focus to heat.